In something small, light, and aerodynamic, you might get around 10 MPG on the freeway on cruise control with no winds or hills, give or take. Some will say you'll get 10 or more, but that's questionable. Any situation that requires invoking the "legendary power" of the V10, will reduce the MPG to nearer 4 or lower as the RPMs increase to provide it.
In our 2016 Sunstar (27' long bread box, ready to travel weight around 13,000 lbs) I figure we got around 6 MPG overall average, for the short time we owned it. We towed a 4500lb Wrangler to get those numbers. On one long trip.